Study of a new water jet thruster for robotic returnable jumping

A novel water jet thruster which is capable of conducting two sequential jumps is proposed for the amphibious jumping robot. The proposed water jet thruster adopted a unique structural design with a double-layered tank. Liquid nitrogen was injected to the tank to pressure the propellant water and generate propulsive force, which is safe and effective for both aquatic and terrestrial environment. Then a theoretical jumping model was built to evaluate the performances of two jumping actions. According to the tethered thrust measurement and free jumping experiments, the estimation from the model met well with their experimental verifications. Moreover, CFD simulation was conducted to compare the emission process of inner and outer chambers in detail. We believe the demonstration of the novel thruster would drive the innovation of future amphibious robots that capable of leaping from both aquatic and terrestrial environments.